Sweet Success: Chocolate Structure Whets Appetite for Innovation

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A delectable design aimed at using innovative materials in
architecture has led to what might be a cocoa lover's wildest
dream: a pavilion made entirely out of chocolate.

Engineers at Princeton University have teamed up with the Belgian
chocolate
company Barry Callebaut — the world's largest chocolate
manufacturer — to construct what would be the first functional
structure made completely of chocolate.

"I think most people just do what has been done before, and I
think that is very restricting," said Sigrid Adriaenssens, a
professor of civil and environmental engineering at Princeton
involved in the project. "I think especially in structural
engineering, a lot of the systems that we use have specific names
and people think that they can only use the systems that already
exist."

The team used such computer programs to minimize the weight of
their chocolate pavilion, having established that the
strength-to-weight ratio of chocolate is quite low — about 24
times lower than standard concrete. They settled on a design
consisting of more than 70 individual frames of chocolate that
puzzle together into an open-air domed pavilion. The empty space
within each frame helps to lighten the load. In total, the
structure consists of about 900 pounds (400 kilograms) of
chocolate.

Members of the research and development branch at Barry Callebaut
helped devise a careful mixture of sugar, cocoa powder, milk
permeate and vegetable oil strong enough to maintain this form
and stay rigid at room temperature.

The resulting product does not technically qualify as "real"
chocolate: Legally, in the United States, the primary fat solid
in marketable chocolate must be
cocoa butter. Still, the material does smell, look and taste
like chocolate, according Mark Adriaenssens, the director of
R&D at Barry Callebaut Americas.

"You can eat it for sure, but it doesn't taste as good as good
Belgian chocolate does, I admit," said Adriaenssens (who has no
relation to Sigrid Adriaenssens). "For structural reasons, we
went with different fat than cocoa butter that resisted
temperature. But because it resists temperature better, it melts
less in your mouth and tastes less good than real chocolate
does."

The group used this concoction to build a 30-by-30-inch (80 by 80
cm) prototype earlier this year, which has since held up on
display at Princeton.

The life-size pavilion — measuring up to 15 feet high and wide
(2.5 meters) — would function as a temporary installation rather
than a permanent structure, lasting up to about a month,
Adriaenssens said.

Have chocolate, need venue

The team originally planned to showcase their work at the grand
opening of the Belgian Beer Café in midtown Manhattan this
summer, but those plans have since fallen through due to
logistical constraints, according to a spokesperson for the
Belgian Beer Café.

But the team has not yet given up on the project, and will
continue to search for a new venue.

"We can make it, we know that, it's just finding the right place
to build it," said Adriaenssens at Barry Callebaut.

Barry Callebaut plans to donate the chocolate for the project,
and while the eventual installation would likely provide the
company with some publicity, Adriaenssens does not expect to make
money from it.

"It's just for fun," Adriaenssens said. "Sometimes that's also
possible."

For the architects involved, the project also offers an academic
opportunity to explore how material can inform design. A report
of their chocolate pavilion development is currently under review
in the journal Computer-Aided Design.